Founding AI Engineer — Amble (Page Nineteen, Ltd.)
May 2025 — PresentJoined at a small-team stage in May 2025 and have shipped through several iterations of the platform. The current 6-person engineering team (3 ML/AI engineers, 1 iOS, 1 designer, 1 founder/PM) came together over the second half of 2025.
Personalised immersive language acquisition platform: multi-persona voice agent tutors, AI-generated articles, FSRS-based vocabulary scheduling.
- Multi-provider STT and audio-LLM evaluation harness. 30 model/method combinations across OpenAI, Gemini, Mistral, and ElevenLabs. 1,500 API calls on real production audio. Consensus-based WER with 95% CIs and p95 latencies, plus Pareto-frontier analysis. Found Mistral Voxtral Mini STT outperforms GPT-4o-transcribe on learner speech at lower cost; the harness doubles as a regression test against vendor model updates.
- TTS provider selection. ElevenLabs Multilingual v2 for conversational tutor personas; Cartesia Sonic 3 for article read-out, where reliable streaming word-level timestamps in non-English languages outweighed raw quality.
- Three-layer voice context injection. Gives the stateless real-time tutor working memory of every prior session. Mem0 with event-anchored timestamps and expiration-aware future facts. Each layer degrades gracefully when an upstream service is unreachable.
- Personalised push notifications. Body copy generated per user by Claude Sonnet from the recommendation feed, timezone-aware APNs delivery, and a content-freshness check that drops the push if the user already saw the content in-app. 5.3x lift in notification-driven opens within the first week of full rollout. 7-state lifecycle across 4 services and 2 Redis queues.
- On-demand article streaming with word-level audio alignment. Built jointly with another backend engineer. SSE from partial-JSON LLM output; sentence-buffered TTS with shifted timestamps yields a contiguous read-along timeline. Generate-once-per-shared-article semantics via a Redis claim.
Supported alongside the team (primarily owned by the other backend/AI engineers): the Pipecat + LiveKit + Modal voice cascade (sub-second turn latency) and the hybrid recommendation engine with two-layer diversity enforcement that addresses LLM topic convergence (the "coffee problem").
Stack: Python, FastAPI, Pipecat, LiveKit, Modal, PostgreSQL, Redis, Mem0, Latitude, OpenAI Realtime, Claude, ElevenLabs, Cartesia, APNs.